Searching by tags can't find any pages

I have multiple pages with tags and I've tried searching with the tags, but it doesn't produce any results.

Here is a picture of the page I'm trying to find and its front matter.
I can find the page by searching for its content but not by searching for its tags.

Problem

This is from the simple search documentation.

By default it [Simple Search] can search Page Titles, Content and Taxonomy (optional).

This makes me think what I'm trying to achieve is achievable but I'm just doing something wrong.

Am I just getting the syntax wrong in the front matter or missing something else?

Hmm.. it should just work, but seems it's a know issue that I have missed: https://github.com/getgrav/grav-plugin-simplesearch/issues/28